How did ancient lower vascular plants contribute to the formation of coal beds?

Ancient lower vascular plants played a fundamental role in the formation of coal beds, particularly during the Carboniferous Period. These plants, which included lycopsids (such as Lepidodendron and Sigillaria) and sphenopsids (such as Calamites), thrived in vast, warm, and humid swamp environments.123

As these plants died, their remains accumulated in low-lying, waterlogged areas where stagnant conditions and a lack of oxygen inhibited complete decomposition. Microorganisms partially broke down the plant material, converting it into peat, which served as the essential precursor to coal. Over time, through the process of geochemical coalification, this buried peat was subjected to pressure and heat as it was covered by layers of sediment. This cycle of plant growth, accumulation, and burial was repeated multiple times, resulting in the extensive coal seams found in the geological record today. Evidence of this botanical origin is preserved in the form of fossilized stems, leaves, and spores found within and adjacent to coal deposits.43